Robert Serber

Fellows:

I'm going to ask some questions about your work with Professor Van Vleck at the University of Wisconsin. You went to Madison in the fall of 1930?

Serber:

That's right, I was a teaching assistant there. Of course, that was the beginning of the Depression, and teaching jobs were very hard to get. I was lucky, because that was about the last year there were available for several years. I got there just in time.

Fellows:

You had a teaching assistantship for three years or four?

Serber:

Four years. When I arrived, Van wasn't actually there. I think he was in Europe. He was on leave for a semester. That would have been the fall semester in 1930.

Fellows:

He was at the Solvay Congress. I think he arrived back from Europe in about the middle of November, but he didn't start the school year there.

Serber:

Yes, that's right. I remember he wasn't there when I arrived, and I just started in, taking over lab sections, and taking courses, and when Van got back, he almost immediately gave me a research problem. In fact, he told me later that he didn't realize I was a first year student,
and he started me right off doing a problem. I forget which was the first. It may have been the Faraday effect or something like that.

Fellows:

You published that I think in '32, so you'd been working on it from your first year anyway.

Serber:

Yes.

Fellows:

He was writing the text on susceptibilities at that time. ^[1] There's an acknowledgment in the preface to you.

Serber:

Yes, you might be interested in [the inscription in my copy] when he gave it to me.

Fellows:

It says "Mr. R. Serber with kind appreciation of your assistance in proofreading."

Serber:

Yes, well, that's what I did. Van wrote the book, in fact, as I recall at that time it was all written and had been sent in to, which press was it, Oxford University?

Fellows:

Oxford. [R.H.]. Fowler was his editor.

Serber:

Yes, and he was getting galley proofs back.

Fellows:

Already?

Serber:

Let's see, [the preface] it was written in June, '31. So that means the beginning of '31 was essentially when it must have started. He was already getting the galleys back.

Fellows:

Yes, I've seen some correspondence with Oxford Press but I don't recall when it started.

Serber:

Anyway, it must have been about then, and I proofread all the galleys for him, not only for typographical errors, but, — I went through

Fellows:

— you checked the calculations?

Serber:

Well, the formulas to see they were right, and checked the general logic, and also, if there was anything I didn't understand, I would ask him, and then he would decide whether it was clear in the text or whether he should make some minor changes to make it more clear. It was sort of a critical proofreading.

Fellows:

[The preface] said, "assistance in the calculations,"

Serber:

I forgot that one. "— and in proofreading." The proofreading was my part. I guess Amelia [Frank] did the assistance in the calculations. I don't remember doing any of that to speak of.

Fellows:

OK. That certainly kept you busy the first year.

Serber:

Yes, it did. I put in a lot of time on that book.

Fellows:

When you started your work in the fall [of 1930], did you start with a course in quantum mechanics the first year?

Serber:

Van wasn't there then so there wasn't any quantum mechanics that fall, and I don't remember whether he started it, the course, in the spring, or whether there wasn't any quantum mechanics that year at all.

Fellows:

You certainly took it the next year.

Serber:

Yes. Well then what happened was, because there weren't any jobs available, none of the graduate students that were there [wanted to finish.] [He] had a very nice bunch, there was Amelia Frank, (and she married Wigner later,) and [Raghar] Rollefson and Whitmore and Bill Penney and [Robert] Schlapp and —

Fellows:

— [K.F.] Niessen? No, Niessen wasn't there at that time, he'd gone.

Serber:

No. You must have the names of the students. Manny Piore was there. He wasn't Van's student but he hung around with us, in the same office.

Fellows:

Was Glenn Havens there at that time?

Serber:

Let me see. Yes, I think so. I wouldn't be sure.

Fellows:

I've spoken to Rollefson but I don't remember all the details.

Serber:

I don't remember, it's such a long time, but they certainly have the record at Madison, who was there. Anyway, it was a nice active bunch of students, and people like Amelia Frank and Rollefson, were consider ably ahead of me, but since there weren't any jobs available, nobody took their Ph.D. They just stayed on, and for the whole four years, there was no turnover. There were no new graduate students coming in and nobody leaving. So Van had the same people all the time.

Fellows:

I read part of that account in your interview with Charles Weiner.^[2] [Van Vleck] would essentially teach another year of quantum mechanics, every time through

Serber:

Yes, he gave the quantum mechanics course. Next year it was the same class again, so he called it quantum mechanics II. And the third year, the next year, quantum mechanics III, it went on for three years.

Fellows:

What subjects do you remember covering?

Serber:

I have all the notes here, if you'd like to see them.

Fellows:

Maybe I can look at them after we get done talking.

Serber:

We all took notes of his lectures and I have them here.

Fellows:

I'd like to know what topics you got to. Did you cover group theory in that course?

Serber:

Yes. He started out with just the principles of quantum mechanics, and then he taught molecular structure and bonding theory, he taught about molecules, and molecular spectra. He taught group theory. He taught chemical reaction rates. He covered most of the applications that were interesting. The thing he didn't cover — I mean, he covered just slightly, the relativistic theory, Dirac theory, just at the end; and he didn't go into field theory or things that were under considerable discussion, Dirac theory, positrons and what not, that he didn't get to.
And I think only a minor amount of nuclear physics, but you can see from the notes exactly what it was.

Fellows:

You worked on the electron theory with Oppenheimer later on?

Serber:

Yes, later on.

Fellows:

Was it required to take quantum mechanics for a graduate student then?

Serber:

I think so. I think everybody took the course.

Fellows:

I know it's now a requirement for first year graduate students, to take quantum mechanics.

Serber:

Yes. I think it was then too. I think everybody took the first course, and then the second and third were just Van's students.

Fellows:

You said you were a teaching assistant all the time you were at Wisconsin. Were you on salary waivers any of those years? Was your salary reduced? I know faculty salaries were.

Serber:

Let me think. I'm trying to remember. I know we started out, we were supposed to get $800 a year, and then there was a reduction to 600. Now, I'm not sure that that applied to the physics department. I know it applied to most of the university. I have a faint recollection that somehow the physics department was excepted but I'm not sure about that. Anyway we got either 800 or 600.

Fellows:

Which was not a lot of money, but it was enough. —

Serber:

Well, yes, but things were cheap. You could get a hamburger for a nickel. Get your dinner for 35 cents at the Student Union, and the rents were about $25 a month or 35, so one could get by.

Fellows:

The NRC paid you more, though, considerably more?

Serber:

Well, not an awful lot. I think it was 1200. I know there's an interesting document. Just look who signed it.

Fellows:

[Reading framed NRC Fellowship certificate of appointment] [R.A.] Millikan, George Birkhoff, Karl Compton, … Charles Mendenhall, Oswald Veblen, [K.F.] Richtmyer …

Serber:

[Abraham] Flexner.

Fellows:

It is Flexner. I couldn't read it.

Serber:

Roger Adams, Gilbert Bliss, [George] Birkhoff, all the big shots were on the committee that gave scholarships in those days.

Fellows:

Pretty good collection of autographs.

Serber:

Yes.

Fellows:

Did you have the fellowship renewed after that?

Serber:

Yes. For another year. That was 1200 I remember.

Fellows:

A princely salary by comparison. I suppose you'd heard of quantum mechanics before you studied it at Wisconsin. Had you any formal study of it at Lehigh?

Serber:

Not really. I'd sort of heard about it. I suppose probably the Bohr theory was mentioned in the atomic physics class I took as an undergraduate, but it was barely more than that.

Fellows:

[Quantum mechanics] was definitely modern physics then.

Serber:

I recall, the course on atomic physics, described things like cathode rays, [J.J.] Thomson's experiment on the electron — it was pretty much experimental, very little interpretation.

Fellows:

Not theoretical. Was the colloquium at Wisconsin mostly concerned with experimental physics? I assume it was.

Serber:

I don't really remember now how it was divided.

Fellows:

There's, in the archives at Wisconsin, the log of the colloquium, which I looked at. Your name turns up more often than Van Vleck's as a speaker.

Serber:

Is that right?

Fellows:

Do you remember if he spoke very often?

Serber:

No, I don't remember.

Fellows:

Well, there's one colloquium that I did write down. He spoke on the Solvay Congress, after he got back, the Solvay Congress of 1930. You took over Van Vleck's courses in 1934.

Serber:

Yes, for a while. I forget — he was going someplace.

Fellows:

He went to Stanford for part of a quarter.

Serber:

Yes, that's right and I remember, he gave me a copy of, wait a minute, what's that book, on scattering theory. [Long pause.] Yes, scattering theory. It came out in 1932 or something like that.

Fellows:

So you were using it in the advanced quantum course?

Serber:

Yes, he told me to study quantum theory, scattering theory, and teach it to the class. I don't know how successful it was. You know, I was just about one step ahead of them. I would study it and the next day go and tell them what I'd read the night before.

Fellows:

It was the same class, though, with all the hangers-on.

Serber:

Yes, that's right. I taught them some scattering theory, which I didn't quite understand very well myself at the time. We also ran a seminar of our own, the graduate students, where we would take some book, in fact we took Whittaker and Watson and we ran through it from cover to cover, with different people reporting every time, each one taking a chapter. ^[3] And I remember Bill Penney gave us a little course on kinetic theory too and hydrodynamics.

Fellows:

I wondered if there was much informal —

Serber:

Well, I mean, that was going on. You see, the same people were there —

Fellows:

So it ran all the time, all the three or four years that you were all there?

Serber:

Yes. I mean, we took Van's course, and we organized our own informal seminars. We gave our own courses to each other.

Fellows:

So there was a Wisconsin theoretical seminar.

Serber:

Oh yes. It went on pretty solidly with quite a few very good people in it. And I guess Penney was there two years, and

Fellows:

I think he was there two [years].

Serber:

Yes, and Schlapp was there, I think, two years also. Of course, they were our seniors. They had already gotten their degrees. We learned a lot from them.
Van, you know, was quite a kind man, and it was a pleasure to work with him. During the day he was usually down in his office and we could go down any time and talk to him about our problem; and occasionally, once or twice a week, he would sort of wander by the offices and make sure everybody was doing all right.

Fellows:

Would you say you worked more closely with him than most students do with their advisors?

Serber:

No, I don't know that I worked any more closely with him than the other students there did. — With Oppenheimer, I did. But Oppenheimer's style was different. With Oppenheimer his whole social life, not his whole social life but a large part of it, was with his students.
It wasn't that way with Van. We went over, I remember being at his house several times for dinner, but it wasn't the normal thing.

Fellows:

I haven't spoken to very many people that worked with him. My impression was that when Van Vleck was working it was usually pretty much his own work, it wasn't very often collaborative.

Serber:

That's right. Yes, he would suggest a problem and he would help you with it a great deal — as much as you asked him to and then a little bit more, — but we didn't collaborate on anything. Everybody, as far as I remember, worked on their own problem.
I didn't write any papers where my name and Van Vleck's were on the same —

Fellows:

Well, Amelia Frank's work, my impression is, was done more closely with Van Vleck than yours was.

Serber:

Yes. She was there before I was, and I think she worked more closely, I mean, helping with the calculations — would be a closer collaboration than reading proof.

Fellows:

Her calculations were very much outgrowths of Van Vleck's work. It seemed to me yours were more independent.

Serber:

Yes, I think that's true, in Amelia's case, but I think work [sic.] say that Penney did and Rollefson and what not, was more like mine. Van would suggest things but he wouldn't actually collaborate on them.

Fellows:

You'd speak to him once or twice a week?

Serber:

Well, he would come around to the office once or twice a week just to see how things were going, and besides, you could always go down to his office and talk to him. I'd speak to him about problems a couple of times a week, that's about how it went.

Fellows:

Was he always able to see through the snags you'd run into? Was he usually [able]?

Serber:

Usually, yes. I don't know about always, but certainly usually.

Fellows:

He was familiar with the problem?

Serber:

— Yes, he was always on top of the problem. He knew the way it should go and could help you out if you got stuck, and give you good advice about how to proceed.

Fellows:

So he'd be following you with the problem.

Serber:

Yes, but as I remember, it didn't require too much of that, at least the problems I was working on. I went through fairly independently. It was more that he gave critical advice on how to write an article up. I remember the first article I wrote came back, and after each equation was a dollar sign — [indicating] how much it would cost to print it in the PHYSICAL REVIEW! It would teach you not write down all the unnecessary steps as you went along.
He taught us all that kind of thing, how to write a paper and how to give a speech at the Physical Society meeting, and —

Fellows:

When did you give your first American Physical Society paper?

Serber:

Let's see, when would it have been? Well, we'd have a Thanksgiving meeting in Chicago. If I went there in '30, it wouldn't have been that year. It probably was in that fall meeting in Chicago in '31.

Fellows:

It would be in the PHYSICAL REVIEW.

Serber:

Yes. It was either '31 or '32, probably '31, the fall Chicago meeting.

Fellows:

And it would have been on the Faraday effect, I suppose?

Serber:

Very likely. I mean, then I also wrote on magnetic rotation spectra, and statistical averages, Dirac vector model, yes, and something about molecules' binding energy. That came towards the end. ^[4]

Fellows:

One of them I think you finished after you'd gone to Berkeley.

Serber:

Yes.

Fellows:

But it was clearly something you'd started before you went out to California.

Well, I had a technical question about Van Vleck's method of pairing perturbation terms. Do you recall that method, where the exponential factors cancel out the energy denominators, in a perturbation expansion? ^[5]

Serber:

You mean, the business of taking — (crosstalk)

Fellows:

— the low — frequency terms, as Van Vleck called them, and pairing them one to another?

Serber:

Yes. There's considerable detail in here.

Fellows:

Right, it's sort of the, the nub of his general theory of gas susceptibilities. Well, you developed it [further] in [one of your papers].

Serber:

Yes, something about statistical averages, in perturbed systems.

Fellows:

Right. Do you know if that method was important in other people's work, was it widely used? I haven't found much reference to it.

Serber:

Well, let me think. There's another way of doing it, less formally. … I think other people must have used it quite a bit, but probably set up formally a little bit differently. One thing I didn't realize when I wrote that paper on statistical averages was that if you considered it to be a Laplace transform with e to the minus beta [times] the mathematics looked a trifle different, but the value came down to the same thing at the end. I mean, you go around —

Fellows:

— integrate. —

Serber:

— Yes, you go around the pole, and then you calculate the residue at the pole, which amounts to the same thing as taking the limits. ^[6]

Fellows:

It sounds a lot simpler to me.

Serber:

Well, mathematically it's cleaner. You just use the formula, the residue at the pole, as the nth derivative of something, and —

Fellows:

Right.

Serber:

That is, when it's a higher-order pole. And I think that's probably the way people did it later on, but of course, it really isn't any different.

Fellows:

Well, I know there were earlier papers in which, instead of expanding the [exponential in a series] it was just integrated directly, and I guess it comes down to the same thing. You're making the same approximation that it's a small quantity and you integrate. Integrate over it.

Serber:

Yes, I mean, it's just a matter of technique, and how you formulate it isn't important.

Fellows:

It was an important [device].

Serber:

The advantage of Van's way of doing it is that it's quite clear what the physics is, that's involved.

Fellows:

Yes. I've been looking at it trying to figure out how he formulated it in the first place, and he seems to have integrated it from a classical expression, before he did the quantum development.

Serber:

Yes. Well, you know, that book of Van's that came out on the old quantum theory, that was really a very fine book. ^[7]

Fellows:

Was he still using it for a text at the time you took [his course].

Serber:

No. But it's a shame, it came out just a little too late, it was a first rate book but it sort of lost its interest because of all the new developments.

Fellows:

It was reprinted in 1928, so it wasn't completely a waste of effort. He did use it as a text in his courses, although apparently not that late. He thought of writing, at one time, another text on quantum mechanics, before he started the susceptibilities text, but I don't know how far he got with that one. I suppose it would have been a parallel to the NRC bulletin.

Serber:

Yes. Well, these books, were almost the end of a long tradition of definitive textbooks, I mean, like Lamb's HYDRODYNAMICS and Whittaker's DYNAMICS. ^[8] People don't write books like that anymore.

Fellows:

No. Well, it's still in print, the susceptibilities text is. Van Vleck was working on the second edition, I'm sure you know, for years, but he never completely finished it.

Serber:

Nope. Did you run into any stories about the calculator that somebody gave Van?

Fellows:

No.

Serber:

Well, we used slide rules. We didn't even have desk calculators. Somebody gave Van a thing, it was about this long, this wide, [about 30" by 18"] big, and it had built in legs so it stood desk high, all solid brass, with elaborate scrolls, and it was called the Millionaire. It had levers, you know, a whole row of levers, you pulled down, you got —

Fellows:

It wasn't electric?

Serber:

No, no. You pulled down, this one in 1, the next one in 6, the next one in 5, then you turned a crank, and it would multiply, or divide or add and subtract for you. As a matter of fact, two or three years ago, down at the IBM building, in their window they had a demonstration of early calculators, and I saw the prototype of Van's in the window.

Fellows:

He had that at Wisconsin?

Serber:

Yes, he had that at Wisconsin. And I remember using it for calculations.

Fellows:

How accurate was it, how many decimal places?

Serber:

Oh, I imagine it had five or six, probably six.

Fellows:

You still could use logarithms.

Serber:

Sure, you used logarithms, trig table, —

Fellows:

If you needed more [accuracy] than you had with a slide rule. I don't know what became of that thing. I haven't heard of it before.

Serber:

Yes. Well, we had a lot of fun with it. The first calculator I ever used.

Fellows:

He talks about using a calculator, borrowing one from the Business School, for his doctoral thesis on the [helium] atom, but apparently it wasn't anything so ostentatious.

Serber:

No, this thing it must have been about 1933, he got hold of it from some place.

Fellows:

In this book on susceptibilities, there's one thing that I'm not entirely sure of. Why is Chapter 3, the one on electric (crosstalk) polarizabilities placed so early in the book, before the introduction of the quantum theory? [The chapter on] dielectric constants, refraction and so forth, —? Is it just because it doesn't depend on the quantum theory?

Serber:

Yes, I think so. I think Van's idea was to give the classical theory first.

Fellows:

Things that you could calculate rigorously with the classical theory.

Serber:

Yes, the ideas in there go back to the 19th century. The definitions and the concepts, and there was that classical theory. As I recall, he did it in that order, first gave the classical theory, and then, afterwards, re-derived them with quantum theory.

Fellows:

It makes sense, it just leaves some of the results, some of the discussion of experimental data in the earlier part of the book, and then there's a long break before you get back to it in the closing chapters.

Serber:

Yes. You can raise the question whether that was the best way of doing it.

Fellows:

Well, when he was revising it, he preserved essentially that structure, so I guess he thought it was still a good way to do it, even 40 or 50 years later.

Serber:

Well, I mean, paying respect to the historical development was worth quite a bit.

Fellows:

I think it's difficult to understand it otherwise.

Serber:

Yes. Of course, when he wrote it, people were much less familiar with quantum theory than they are now, and I think there was much more reason for it then than there would be now. Nowadays, students understand quantum theory better than they understand classical theory —

Fellows:

The chapter on quantum foundations, as I understand, was sometimes used as an introductory text on quantum theory.

Serber:

That's very good and very clear. The relations with the classical theory are explained very nicely there.

Fellows:

Was Dirac's quantum theory text out? Was it something you used in your graduate work?

Serber:

No, it wasn't something we used, but Van recommended that we read it, and I remember going through it page by page, when I was in Madison, reading the whole thing, and I think what field theory Van gave was based on the treatment in that book. ^[9]

Fellows:

Dirac visited Madison in '31, I think. Did you meet him when he was there?

Serber:

I don't remember. I don't remember meeting him until after I was in California, when he visited there. When I was a first year graduate student if Dirac were there I would have heard him talk, but I wouldn't have seen him otherwise.

Fellows:

Fowler was there.

Serber:

Yes, I remember. I remember that quite distinctly. Yes, Fowler gave several lectures. I think I have notes of one or two.

Fellows:

I'll have to look at those. Was he a good lecturer?

Serber:

Yes. Fowler was very good. Yes, he talked about transport phenomena in statistical mechanics.

Fellows:

I think I may have seen someone's notes on that at the Wisconsin archives, maybe [L.R.] Ingersoll's notes. I suppose all the faculty would have sat in on Fowler's lectures?

Serber:

Yes.

Fellows:

At Minnesota, [J.T.] Tate and others would sit in on Van's quantum mechanics lectures, to see what they could pick up.

Serber:

Yes, well, the faculty didn't do that at Wisconsin.

Fellows:

Well, it wasn't quite so new.

Serber:

Yes, that's right.

Fellows:

Well, I was wondering what the title of your thesis^[10] was. There are several papers — I wouldn't know what common title to put on them.

Serber:

Yes, well, that was a joke. At the time I took my Ph.D. final, I remember, they asked me what the title of my dissertation was, and I couldn't recall — I had discussed with Van which paper to put in as my dissertation, but I couldn't remember which one we'd decided on! So when they asked me the title, I couldn't remember. I forgot which one we finally took.

Fellows:

Do you remember which one now?

Serber:

No, I don't remember now.

Fellows:

I neglected to check that when I was at Wisconsin.

Serber:

I remember, we picked out either one or one or two on the same subject, and then I forgot which ones.

Fellows:

There's a name I've run into once or twice, a fellow named Janes at Wisconsin. Do you know who he was?

Serber:

No, I don't remember that at all.

Fellows:

Well, there were letters between Van Vleck and Mendenhall trying to get a fellowship or assistantship for him in 1933.

Serber:

No, I don't remember him.

Fellows:

I don't think I've ever heard his name anywhere else. I wondered if you knew anything about him. Did Van Vleck do more traveling than most of the faculty at that time?

Serber:

Well, probably more than most of the rest of the Wisconsin faculty. He traveled about as much as Oppenheimer did, a little later. He went away several times to meetings.

Fellows:

I find lots of references to lectures, he'd go down to Iowa and give a lecture, he'd go to Paris and give a paper, something like that.

Serber:

Yes. He did travel around quite a bit for those days, when the government wasn't paying your fare.

Fellows:

Well, he wasn't poor.

Serber:

Neither was Oppenheimer. I think they traveled more than most. Although universities, I guess, often managed to scrape up enough money for —

Fellows:

— to pay at least part of —

Serber:

— their speakers.

Fellows:

Well, that got more difficult after the early thirties.

Serber:

Yes, I mean, there really wasn't any money at all to spare.

Fellows:

I'm getting to the end of my questions.. Is there anything else you think of?

Serber:

— well, let me see if I think of anything that might be interesting. No, I mean, that's the general impression. It was a very fine school of theoretical study, there, at the time. It — The Oppenheimer school, you know, was much more widely known, but that's because — you know also, one of the reasons is that it went on for a longer time. Van's [school], one trouble with it was a limited number of people because of the Depression — there were only a few people, and they turned out very well, on the whole, a very successful bunch. But then Van left, shortly thereafter, and that Wisconsin school never — It was great while it lasted, though not so well known. As I say Van was a very good, fine man, to work for, very helpful, and very kind, looked after his students very well, and taught us very well. He was a very good teacher.

Fellows:

He was quick enough to be able to be on top of your problems.

Serber:

Yes. On the other hand, now, Oppenheimer had this inspirational quality, which Van didn't have, and one of the big reasons was that Oppenheimer was treating different kinds of problems, not so much applications of quantum theory but really at the forefront of unsolved problems, and that made it considerably more exciting, to work with Oppenheimer.

Fellows:

There's a passage, I think, I've forgotten to whom, but Van Vleck was writing that when Oppenheimer talked, Van would just stand there open mouthed, in awe. Well, Oppenheimer I've heard described as being erudite. It was obvious from the moment you met him that he was brilliant. Would you say it was that way with Van Vleck?

Serber:

Well, I don't know. Oppenheimer, first of all, he was extremely verbal. You know, he spoke very well, and — he had a completely impressive personality. [Telephone — noise]

Fellows:

Thank you very much.